The invention is based on a priority application (EP 02360074.5) which is hereby incorporated by reference.
The invention relates to a process for determining the radio reception direction on the downlink in a radio base station location in a mobile communications network according to the preamble of claim 1. The invention further relates to a mobile communications network with devices, in particular with a computer, a radio base station and a mobile communications terminal, for the implementation of the process according to the preambles of the subsidiary claims.
In mobile communications networks, in particular in cellular mobile communications networks, such as for example GSM (Global System for Mobile Communications) or UMTS (Universal Mobile Telecommunications System), it is important to know the instantaneous location of the mobile subscribers. So-called “location based services”, i.e., mobile services dependent on the instantaneous location of the mobile subscribers, are of increasing interest. To be able to perform these and similar services, it is not only necessary to know the radio cell or radio field section in which the radio subscriber is located, but also to perform a more accurate position determination down to a few meters. Various methods are known for achieving this. Thus for example the so-called triangulation method is known, in which the distances between the mobile communications terminal and adjacent fixed ratio stations are calculated by measuring radio signal propagation times, the instantaneous location being determined on the basis of the intersection points of corresponding distance radii. For this purpose however there must be contact with at least two remote radio base stations. In addition, the radio transmitters of the radio base stations must be synchronised with one another, or at least the time differences between the transmitted signals, in particular between the symbols, must be known.
It is also known to firstly determine the radio reception direction by analyzing radio signal components present at group antennae, so-called smart antennae.
Then, in addition, the distance to the radio base station is also calculated (by measuring the signal propagation time) so that finally the location can be more accurately determined. However, the known processes involve a not inconsiderable computational outlay and have specific prerequisites, such as for example contact with a plurality of radio base stations or the presence of group antennae.